A door lock of the above mentioned kind has been previously disclosed, for example, in DE 196 53 169 A1 (FIG. 26). This vehicle door lock exhibits a flat, rectangular lock case 200 (referring to the element number used in that reference) having a horizontal base wall 201 of the case, a case cover (not illustrated) arranged parallel thereto, two horizontal transversal case walls 202 and 203 running perpendicular to the base wall 201 of the case, and two vertically oriented longitudinal case walls 204 and 205, which door lock is arranged on a vehicle door (not illustrated) of a vehicle and contains the component parts necessary for its locking closure. In the direction towards a lock pin 206 projecting horizontally on the door pillar, the base wall 201 of the case and the longitudinal wall 204 of the case have a recess 207, in which the lock pin 206 is accommodated with the door in its closed state.
Adjacent to the recess 207 above and below this and arranged vertically in alignment with one another and slightly apart from one another, each lock case 200 has a rotary latch 209 capable of pivoting about a rotary latch swivel pin 208. The rotary latches 209 are plate-shaped elements, which has noses 210 projecting outwards beyond the lock case 200 in the direction of the lock pin 206. Each of the noses 210 has a throat 211 in a peripheral wall 212 of the rotary latch 209. The throats 211 in the noses 210 face one another.
Provided in addition are two rotary latch spiral springs 213, of which only one is represented, which are arranged around the rotary latch swivel pins 208. These rotary latch spiral springs 213 are supported in each case by a spring limb on a projecting part 214, which is formed on the rotary latches 209 lying more or less diametrically opposite the throats 211 and by a second spring limb internally on the longitudinal wall 204 of the case (not illustrated), and endeavor to hold the rotary latches 209 in an opened position, that is to say to force apart the noses 210 which face one another.
Furthermore, two adjacent and essentially V-shaped detent recesses 215 and 216 are each introduced into the peripheral walls 212 of the rotary latches 209, the detent recesses 215 and 216 lying opposite both rotary latches 209 with the lock in the open position.
In the vicinity of the lock case 200 lying opposite the recess 207, a detent lever or a locking pawl 217 is arranged between the rotary latches 209 and the longitudinal wall 205 of the case. The detent lever 217 is capable of pivoting about a detent lever swivel pin 218, which is arranged horizontally in a corner area of the lock case 200 adjacent to the longitudinal wall 205 of the case and the transversal wall 202 of the case. Formed at one end of the detent lever 217 is a locking piece 219 facing towards the rotary latches 209, which locking piece exhibits two end edges 220 and 221 and, on the rotary latch side, a longitudinal edge 222 connecting the end edges 220 and 221, in conjunction with which a longitudinal edge throat 223 is introduced into the longitudinal edge 222, so that a lever detent nose 224 and 225 is produced in each case. The locking piece 219 in the open position initially makes contact with the lever detent noses 224 and 225 on the peripheral wall 212 of the rotary latches 209 under the effect of the pressure exerted by, for example, a spiral detent lever spring (not illustrated), which spring is arranged, for example, around the detent lever swivel pin 218 and is supported by its detent lever spring legs on the longitudinal wall 205 of the case and on a lever bolt 226 provided at the free end of the detent lever 217.
When a vehicle door is closed, the lock pin 206 that is arranged horizontally on the door pillar arrives in the vicinity of the throats 211 in the rotary latches 209. Through the effect of the pressure exerted by the lock pin 206 on the rotary latches 209, these are caused to pivot about the rotary latch swivel pins 208 against the pressure of the rotary latch spiral springs 213 in a mutually opposite direction of rotation. As a result of the rotating movement, the noses 210 arrive at a position behind the lock pin 206 and engage around it. In the closed position, the lock pin 206 is situated between both of the rotary latches 209 in the vicinity of the throats 211. Pivoting of the rotary latches 209 initially causes the first V-shaped detent recesses 215 to arrive in the vicinity of the locking piece 219, in conjunction with which, as a result of the pressure of the detent lever springs, the lever detent noses 224 and 225 latch into the first detent recesses 215. In this so-called safety catch position, the lock is not completely closed, although it can no longer be opened because of the locking effect of the detent lever 217. In the event of further pivoting of the rotary latches 209, the locking piece 219 together with the lever detent noses 224 and 225 arrives in each case in a second detent recess 216 in the rotary latches 209 and latches in position there. Each of the rotary latches 209 is now supported by the flanks of the detent recesses 216 on a flank of the lever detent noses 224 and 225 of the detent piece 219 and is retained in this way in the closed position against the pressure exerted by the rotary latch springs 213.
Opening the vehicle lock, and with it the door, will cause a system of levers (not illustrated) present in the door to be actuated. This system of levers exhibits a U-shaped lever, which acts on the lever bolt 226 of the detent lever 217, for example, or is executed in a single piece with the detent lever 217 and forces this out from the detent recesses 215 or 216 against the pressure exerted by the detent lever spring and the rotary latch springs 213. If the lever detent noses 224 and 225 have left the detent recesses 215 and 216, the rotary latches 209 engage back into their initial position under the effect of the rotary latch springs 213, that is to say the opened lock position. The lock pin 206 is moved outwards from the lock case 200 by the flanks of the throats 211.
This vehicle lock according to the prior art has proven its worth in service. However, vehicle doors, in particular in agricultural vehicles, are increasingly manufactured from glass and have a tendency to become larger and heavier, so that a weight of 70-80 kg is imposed on the locks of these doors in some cases. The consequence of this is that the vehicle locks must also be made increasingly large and robust, in conjunction with which the release forces required to open and close the vehicle locks also increase due to their physical dimension. Furthermore, the geometry of the detent noses of the two rotary latches and the geometry of the detent lever is relatively intricate in terms of its design and manufacture, as everything is required to be accurately matched, and the detent noses exhibit a different physical form because of the pivoting movement of the detent lever.
A further problem area associated with heavy vehicle doors of this kind is the high forces which act on the rotary latches and the lock pins in conjunction with opening and closing the vehicle doors in the event that the vehicle door is no longer hung in a precisely centered manner, as a consequence of which the lock pin is not introduced into the throat and the rotary latches in a precisely centered manner, but slides along one side of the throat, and the vehicle door with its high weight is only centered during the closing operation. If excessively high forces act on the lock pin, this can lead to bending or even fracture of the lock pin. In any case, the service life of a door lock of this kind is reduced significantly by these high forces.
The object of the invention is to provide a vehicle door lock, which can be manufactured economically and simply, is easy to assemble, and in which the release forces required to be applied for opening and closing are as small as possible. A further object of the invention is to make available a vehicle door lock, in which the forces acting upon the lock pins and the rotary latches are significantly reduced in the case of a vehicle door that is hung out of alignment.
These objects are achieved in accordance with the present invention.